Method of and apparatus for agitating mixtures



Apri 16, m5 s. 1... JOHNSON 1,9929% j METHOD OF AND APPARATUS FORAGITATING MIXTURES g I 3 WWW,

AYJZWJ 0 5M022,

WWW

'3 persons with different degrees of thoroughness the minor axisthereof, whereby emcient agitaf o Patented Apr. 16, 1935 Q 'UNITEDSTATES PATENT FFICE METHOD OF AND APPARATUS FOR AGITATING MIXTURESSilvie Lloyd Johnson, Catonsville, Md.

7 Application November 15, 1934, Serial No. 753,207 I 10 Claims. (01.25957) This invention relates to methods of and appa- Figure 4 is afragmentary view in rear elevation ratus for agitating mixtureamoreparticularly of a tube-supporting spider.

mixtures of blood and diluents, as, for example, In accordance with myimproved method, the

mixtures formed in the preparation of blood b ood sample and diluent arep ac d in a Suitable 5 specimens for microscopic examination. Al-Vessel, Preferably a P p tube formed With though th th and apparatus inaccordance bulb, and the tube is moved in an orbital circular with myinvention may be used for the agitation path about a substantiallyhorizontal axis at a of the i t thgy were developed t peradial distancefrom the axis and at a rotative i l regard to the requirements of suchtu speed so mutually related that the constltuentsof 10 f blood anddiluents and the invention as the mixture will move back and forth inthe bulb 10 1 f h and will not be held in the outermost confines of gagWm be described for t V the bulb by centrifugal force. It W111 be appre-In the preparation of blood Samples for 3119413 ciated that, if therelation between the radial .dis- 'sis'or study the usual procedure isto place a tance of the vessel Irom the axis of rotation and measuredquantity ofthe blood in a pipette tube the speed of rotatlfm are somljltuauy related h formed. with a capillary opening and with anenconsldqmble centnfugal force i w a largement or bulb intermediate theends of the We W111 be thrcwn out aemtihewrrmPSt opening, and to dilutethe sample'in the tube with W of P t? that E ofithem a measured quantityof suitable'fiuid, the amount herough mtermlxl'ng of M16 onstituents and1 a form suspensionof blood corpuscles the co and nature of the diluentdepending upon the um r L kind of study to be made. The mixture thuslatter Wm be thrown 130 outelmost eonfinesgf i Y the bulb and will besegregated from the fluid i r forged f i m ig eqect E1101 constituents.Ittherefore is important that the .gg g fg g gg :2? ggi gg i radialdistance of the-bulb from the axis of rotaf Sp y tion and the speed ofrotation be so related that 2:: throughout the mixture in suspenslon.Her-etc- 7 no substantial centrifugal force is exerted. In fore theagitation has been eficcted by manual Shaking of the pipette tubes and,if the manual accordance with aturther feature of my improved u areobtained WT 1t 15 utmmfnmon so that the major axes of the bulbs aredisposed -30 tor the thoroughness of the manual agitation toatanvoblique angle to the axiq of rotation Whe-n if P and fact tubesthus disposed areirotated at a low speed, cia'bly dii-f-erent resultshave been observed in the fluid mixture contained in the bulbs Wm makingmlmlyses {of the m 9 t slosh around in the bulb, moving both in thedisamples of WhlCh' were prepa by 'dlfierent rection of the major .axisand in the direction of o i g .tion and thorough :mixing are effected. Imay obJeot myfmveliltlon mf also employ the usual bead in the pipettetube method of end-Weeding fgrraigltatmg mlxtures bulb which tumblesaround and assists in the I of' bloo'd andidiluentiinsuch manner as toassure formation of afun'iform mixture -40 uniform and thorough mixing.A further object The amount of b hm force tending to 40 is to provide:such :amethod andapparatus-as-are throw the fluid mixture outwardly ddslu capable of effecting the desired uniform and the acceleration f themixture inwardly toward thomughlmlxmgiieale'sser time than heretpforethe axis of rotation. and this acceleration is sexhas :been required.Other objects will-becomeappressed by the formula: I parent from thefollowing detailed description, p

the appended :claims, and the accompanying a=41r2n213 drawing, vinwhich: where a is the acceleration in inches per second Figure l is :aperspective view of an-apparatus per e d, i the revolutions .per second,and r embodying t ve t V is the radial distance of the mixture from thefi 2 a View the appa s Shown i axis of rotation in inches. Throughexperiments I Figure p y in elevation p -y in verbiand tests in thepreparation of actual samples calsection,and dwW fi efi d subsequentlysubjected to microscopic studies, I Figure 3 is a View in elevation of apipette v13111136 have ascertained that best results are obtained :andan elastic band associated therewith and when theval'ue oftheacceleration a is about one 555 showniinsectiomiand 'hundred'inchespersecondper second. When the radial distance from the axis of rotation andthe rotative speed are so mutually related that the acceleration hasapproximately this value, the fluid is not flung outwardly against theouter walls of the bulb, but is permitted to slosh back and forth underthe combined action of the rotative movement and gravity.

One suitable form of apparatus capable of effecting agitation inaccordance with the invention is shown in the drawing as including astandard A comprising a base i and an upright portion 2, and a motor Bmounted on the standard by means of posts 3 and provided with the usualcord 4 housing electrical conductors. The motor shaft 5 is provided witha pinion 6 meshing with a gear l which has secured to it a pinion 8which meshes with a gear 9 secured to a driven shaft 49.

A spider or tube support C having a hub ll formed with a square openingl2 fitting over-a square portion l3 on the shaft it: is secured inposition on the shaft by means of a wing nut i4 and a washer 55 disposedbetween the wing nut and the hub Ii. The spider C is provided with aplurality of arms i6 which are formed at their outer ends with loops l1,each loop being pro vided with an opening I8 and a second opening I!)spaced from the opening [8. Each opening [9 is formed as a bayonet slothaving a smaller opening portion Ill and a larger opening portion [9 Thepairs of openings l8 and iii serve conjointly to form seats forreceiving pipette tubes D, E, F, and G which are formed respectivelywith oval bulbs or mixing vessels D E F and G and preferably tumblingbeads D E F, and G are located respectively in the bulbs D E F and G Thepipettes are open on both ends, and in order to close the ends of thetubes during agitation I prefer to employ rubber or other elastic bandsD E F and G passing respectively over the opposite ends of the tubes D,E, F, and G and alongside the latter.

After the blood sample and diluent have been placed in the tubes and theelastic bands applied to the latter, the tubes with the bands thereonare inserted through the larger opening portions of the bayonet slots I9and are projected through the openings I8 until the bulbs are disposedwithin the loops I! and between the openings I8 and 19. The tubes arethen moved from the larger openings IS of the bayonet slots into thesmaller openings I9 thereof, and are held in this position by means ofthe rubber bands which serve to cushion the tubes in their seats and toadapt the seats for tubes of different sizes, it being understood thatthe tubes may vary in size depending upon the nature of the examinationto be made.

Tests have indicated that more thorough mixing of the blood and diluentcan be eifected in "a shorter time when the tubes are disposed at anoblique angle to the axis of the shaft H! because this arrangementresults in movement of the mixture in at least two directions, i. e., inthe direction of the major axes of the bulbs and also in the directionof the minor axes thereof. Although the exact amount of angularity isnot critical, I have found that substantially better results .areobtained when the angle a between the shaft axis and the axes of thetub-es is from forty-five to sixty-five degrees, and preferably theangle should be about fifty-five degrees.

As previously stated, it is important that the mixture be not thrownoutwardly appreciably by centrifugal force. With the bulbs of thepipette tubes disposed at a given distance from the axis of rotation,the tendency to throw the mixture outwardly will depend upon therotative speed, and, conversely, for any particular rotative speed thistendency will depend upon the radial dis tance of the bulbs from theaxis of rotation. Thus these two factors may be varied somewhat withinpractical limits, but their mutual relation should be such that nosubstantial centrifugal force is produced, and as a rough measure therelation should be such that the acceleration of the mixing vesselstoward the axis of rotation is about one hundred inches per second persecond. In the embodiment shown in the drawing, and as actuallyconstructed and used in practice, the radial distance of the bulbs fromthe axis of rotation has been between two and a half and two andthree-quarters inches, depending upon the seating of the tubes in theirseats, which may vary to some extent owing to the flexibility of theseating arrangement. With the bulbs disposed at this distance from theaxis of rotation, a rotative speed of one revolution per second has beenfound to produce the best results, and with this mutual relation betweenthe radial distance from the axis of rotation and the rotative speed theacceleration is approximately one hundred inches per second per second.

It will be understood that within practical limits any number of armsmay be provided on the spider C for carrying tubes, so that a largenumber of samples may be prepared for examination at the same time. Theembodiment of the invention disclosed herein has been found to operateefficiently and to obtain the desired results, but it will be understoodthat various changes may be made in the specific construction andrelative arrangement of the parts without departing from the inventionas defined in the claims.

I claim:

1. The method of agitating mixtures to form suspensions which comprisesmoving a vessel containing the constituents of the mixture in a circularpath about a substantially horizontal axis and at a radial distance androtative speed so mutually related that the acceleration of theconstituents towards said axis is approximately one hundred inches persecond per second.

2. The method of agitating mixtures to form suspensions which comprisesmoving an oval vessel containing the constituents about a substantiallyhorizontal axis'with the major axis of said vessel inclined to saidsubstantially horizontal axis at an angle of from forty-five degrees tosixty-five degrees and at a radial distance and rotative speed somutually related that the acceleration of the constituents towards saidaxis is approximately one hundred inches per second per second.

3. The method of agitating mixtures to form suspensions which comprisesmoving an oval vessel containing the constituents about a substantiallyhorizontal axis with the major axis of said vessel inclined to saidsubstantially horizontal axis at an angle of from forty-five degrees tosixty-five degrees and at a radial distance and rotative speed somutually related that the constituents will move in said vessel both inthe direction of the major axis and in the direction of the minor axis,and will not be held in the outermost confines of the vessel bycentrifugal force.

4. The method of agitating mixtures of blood and diluent which comprisesmoving an oval vessel containing the constituents about a substantiallyhorizontal axis with the major axis of said vessel inclined tosaidsubstantially horizontal axis at an angle of from forty-five degreesto sixty-five degrees and at a radial distance and rotative speed somutually related that the constituents will move in said vessel both inthe direction of the major axis and in the direction of the minor axis,and will not be held in the outermost confines of the vessel bycentrifugal force.

5. Apparatus for agitating mixtures to form suspensions comprising asubstantially horizontal rotatable shaft; a support fixed to said shaft;a pipette vessel for containing the ingredients of said mixture andbeing mounted on said support and spaced from the axis of said shaftwith its major axis inclined with respect to said shaft; and means forrotating said support and said vessel about the axis of said shaft.

6. Apparatus for agitating mixtures to form suspensions comprising asubstantially horizontal rotatable shaft; an arm secured to said shaft;a pipette tube formed with a bulb and supported on said arm at an angleof from forty-five degrees to sixty-five degrees with respect to saidshaft, the bulb being spaced to one side of said shaft; and means forrotating said shaft.

7. Apparatus for agitating mixtures to form suspensions comprising asubstantially horizontal rotatable shaft; an arm secured to said shaft;a pipette tube formed with a bulb and supported on said arm at anoblique angle with respect to said shaft, the bulb being spaced from theaxis of the shaft; a tumbler bead in said bulb; and means for rotatingsaid shaft.

8. In apparatus for agitating mixtures to form I suspensions, thecombination of a shaft; an arm carried by said shaft and formed with atubereceiving seat; a pipette tube in said seat; and an elastic bandpassing over both ends of the tube and extending alongside of the tubeand between the latter and said seat.

9. In apparatus for agitating mixtures to form suspensions, thecombination of a shaft; means carried by said shaft provided with aplurality of tube-receiving seats adapted to receive pipette tubes ofvarying sizes within limits; a tube in one of said seats and being openat at least one of its ends; and an elastic band stretched over the endsof said tube and extending alongside of the tube between and inengagement with the latter and said seat whereby to close'the open endof said tube and also to adapt the seat to the size of the tube.

10. In apparatus for agitating mixtures to form suspensions, thecombination of a pipette tube having a bulb intermediate its ends; and arotary support for said tube, said support being provided with twospaced openings, both of which are large enough to embrace said tube andone of which is formed as a bayonet slot, the larger opening of which islarge enough to permit passage of said bulb.

S. LLOYD JOHNSON.

